The current interest in laser radar systems has created a need for determining the reflectance properties of the many materials from which the targets for such systems are made. These targets are generally very complicated and are of such a size that the optical radar cross sections are almost impossible to measure in the far field. Therefore, much effort has been expended to develop computer codes for calculating these cross sections. Part of the necessary input data for these codes consist of the detailed reflectance properties of the materials from which the surfaces of the targets are made. To obtain these surface properties an instrument which might be called a reflectometer is used. These instruments utilize the laser of interest to the optical radar system and measure the reflected energy from the surface of material samples as the angle of incidence is varied. The angle of incidence is usually varied by rotating the sample, but this causes the angle for specular reflection to change by twice the angle through which the sample is rotated, and the detector has to be realigned for each angle of incidence.
Therefore, it is an object of this invention to provide an instrument which avoids the necessity for realigning the detector and thereby provides for a continuous recording of the specular reflectance as a function of the angle of incidence.
Another object of this invention is to provide a device which records reflectance as a function of the angular deviation of the detector from the specular angle for any fixed angle of incidence.
Still another object of this invention is to place a mirror on a rotating platform at a dihedral angle from the sample with the axis of rotation being at the apex of the dihedral angle formed by the mirror and sample.
Still another object of this invention is to provide a device in which a potentiometer type indicator is used to measure the angle of incidence.
A further object of this invention is to provide a device in which the reflected light beam from the mirror is always aligned on the detector.
A still further object of this invention is to provide a reflectometer with a continuous read out.
Other objects and advantages of this invention will be obvious to those skilled in this art.